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release-22.2: opt: add setting to always use histograms to calculate stats #98230

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Mar 8, 2023
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release-22.2: opt: add setting to always use histograms to calculate stats #98230

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4 changes: 4 additions & 0 deletions pkg/sql/exec_util.go
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Original file line number Diff line number Diff line change
Expand Up @@ -3391,6 +3391,10 @@ func (m *sessionDataMutator) SetOptimizerUseImprovedSplitDisjunctionForJoins(val
m.data.OptimizerUseImprovedSplitDisjunctionForJoins = val
}

func (m *sessionDataMutator) SetOptimizerAlwaysUseHistograms(val bool) {
m.data.OptimizerAlwaysUseHistograms = val
}

// Utility functions related to scrubbing sensitive information on SQL Stats.

// quantizeCounts ensures that the Count field in the
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1 change: 1 addition & 0 deletions pkg/sql/logictest/testdata/logic_test/information_schema
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Expand Up @@ -4773,6 +4773,7 @@ null_ordered_last off
on_update_rehome_row_enabled on
opt_split_scan_limit 2048
optimizer on
optimizer_always_use_histograms off
optimizer_use_forecasts on
optimizer_use_histograms on
optimizer_use_improved_disjunction_stats off
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3 changes: 3 additions & 0 deletions pkg/sql/logictest/testdata/logic_test/pg_catalog
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Expand Up @@ -2806,6 +2806,7 @@ node_id 1 NULL
null_ordered_last off NULL NULL NULL string
on_update_rehome_row_enabled on NULL NULL NULL string
opt_split_scan_limit 2048 NULL NULL NULL string
optimizer_always_use_histograms off NULL NULL NULL string
optimizer_use_forecasts on NULL NULL NULL string
optimizer_use_histograms on NULL NULL NULL string
optimizer_use_improved_disjunction_stats off NULL NULL NULL string
Expand Down Expand Up @@ -2947,6 +2948,7 @@ node_id 1 NULL
null_ordered_last off NULL user NULL off off
on_update_rehome_row_enabled on NULL user NULL on on
opt_split_scan_limit 2048 NULL user NULL 2048 2048
optimizer_always_use_histograms off NULL user NULL off off
optimizer_use_forecasts on NULL user NULL on on
optimizer_use_histograms on NULL user NULL on on
optimizer_use_improved_disjunction_stats off NULL user NULL off off
Expand Down Expand Up @@ -3086,6 +3088,7 @@ null_ordered_last NULL NULL NULL
on_update_rehome_row_enabled NULL NULL NULL NULL NULL
opt_split_scan_limit NULL NULL NULL NULL NULL
optimizer NULL NULL NULL NULL NULL
optimizer_always_use_histograms NULL NULL NULL NULL NULL
optimizer_use_forecasts NULL NULL NULL NULL NULL
optimizer_use_histograms NULL NULL NULL NULL NULL
optimizer_use_improved_disjunction_stats NULL NULL NULL NULL NULL
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1 change: 1 addition & 0 deletions pkg/sql/logictest/testdata/logic_test/show_source
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Expand Up @@ -105,6 +105,7 @@ node_id 1
null_ordered_last off
on_update_rehome_row_enabled on
opt_split_scan_limit 2048
optimizer_always_use_histograms off
optimizer_use_forecasts on
optimizer_use_histograms on
optimizer_use_improved_disjunction_stats off
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5 changes: 4 additions & 1 deletion pkg/sql/opt/memo/memo.go
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Expand Up @@ -161,6 +161,7 @@ type Memo struct {
useImprovedDisjunctionStats bool
useLimitOrderingForStreamingGroupBy bool
useImprovedSplitDisjunctionForJoins bool
alwaysUseHistograms bool

// curRank is the highest currently in-use scalar expression rank.
curRank opt.ScalarRank
Expand Down Expand Up @@ -217,6 +218,7 @@ func (m *Memo) Init(evalCtx *eval.Context) {
useImprovedDisjunctionStats: evalCtx.SessionData().OptimizerUseImprovedDisjunctionStats,
useLimitOrderingForStreamingGroupBy: evalCtx.SessionData().OptimizerUseLimitOrderingForStreamingGroupBy,
useImprovedSplitDisjunctionForJoins: evalCtx.SessionData().OptimizerUseImprovedSplitDisjunctionForJoins,
alwaysUseHistograms: evalCtx.SessionData().OptimizerAlwaysUseHistograms,
}
m.metadata.Init()
m.logPropsBuilder.init(evalCtx, m)
Expand Down Expand Up @@ -356,7 +358,8 @@ func (m *Memo) IsStale(
m.variableInequalityLookupJoinEnabled != evalCtx.SessionData().VariableInequalityLookupJoinEnabled ||
m.useImprovedDisjunctionStats != evalCtx.SessionData().OptimizerUseImprovedDisjunctionStats ||
m.useLimitOrderingForStreamingGroupBy != evalCtx.SessionData().OptimizerUseLimitOrderingForStreamingGroupBy ||
m.useImprovedSplitDisjunctionForJoins != evalCtx.SessionData().OptimizerUseImprovedSplitDisjunctionForJoins {
m.useImprovedSplitDisjunctionForJoins != evalCtx.SessionData().OptimizerUseImprovedSplitDisjunctionForJoins ||
m.alwaysUseHistograms != evalCtx.SessionData().OptimizerAlwaysUseHistograms {
return true, nil
}

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6 changes: 6 additions & 0 deletions pkg/sql/opt/memo/memo_test.go
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Expand Up @@ -334,6 +334,12 @@ func TestMemoIsStale(t *testing.T) {
evalCtx.SessionData().OptimizerUseImprovedDisjunctionStats = false
notStale()

// Stale optimizer_always_use_histograms.
evalCtx.SessionData().OptimizerAlwaysUseHistograms = true
stale()
evalCtx.SessionData().OptimizerAlwaysUseHistograms = false
notStale()

// Stale data sources and schema. Create new catalog so that data sources are
// recreated and can be modified independently.
catalog = testcat.New()
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3 changes: 3 additions & 0 deletions pkg/sql/opt/memo/statistics_builder.go
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Expand Up @@ -2808,6 +2808,9 @@ func (sb *statisticsBuilder) finalizeFromRowCountAndDistinctCounts(
}

func (sb *statisticsBuilder) shouldUseHistogram(relProps *props.Relational) bool {
if sb.evalCtx.SessionData().OptimizerAlwaysUseHistograms {
return true
}
// If we know that the cardinality is below a certain threshold (e.g., due to
// a constraint on a key column), don't bother adding the overhead of
// creating a histogram.
Expand Down
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